Java递归查询树形列表。

需求是前端需要树形结构的选择器，所以需要给前端提供树形结构的数据

直接贴代码！！！

 @RequestMapping(method = RequestMethod.POST, value = "/queryTreeList")
    public void queryTreeList(HttpServletRequest request,HttpServletResponse response,@RequestBody Map param){
        try {
            List<Map> res = new ArrayList<>();
            QueryWrapper<BuiSyFunction> wrapper = initWrapper(param);
            wrapper.eq("state",1);
            wrapper.eq("function_parent_id",0);
            //查询所有一级菜单
            List<BuiSyFunction> functions = buiSyFunctionService.list(wrapper);
//            List<Object> list = new ArrayList<>();
            //遍历一级菜单
            for (BuiSyFunction function : functions){
                Map map = new HashMap();
                Long id = function.getId();
                map.put("value",id);
                map.put("label",function.getFunctionName());
                //递归查询子级菜单
                List<Object> childFunctions = getChildFunctions(id);
                if (childFunctions.size() > 0){
                    map.put("children",childFunctions);
                }
                res.add(map);
            }
            renderResult(response,res);
        }catch (Exception e){
            e.printStackTrace();
        }
    }
    public List<Object> getChildFunctions(Long parentId){
        List<Object> res = new ArrayList<>();
        QueryWrapper<BuiSyFunction> wrapper = new QueryWrapper<>();
        wrapper.eq("state",1);
        wrapper.eq("function_parent_id",parentId);
        //根据父Id查询菜单
        List<BuiSyFunction> functions = buiSyFunctionService.list(wrapper);
        for(BuiSyFunction function : functions){
            Map map = new HashMap();
            Long id = function.getId();
            map.put("value",id);
            map.put("label",function.getFunctionName());
            //递归查询子级菜单
            List<Object> childFunctions = getChildFunctions(id);
            if (childFunctions.size() > 0){
                map.put("children",childFunctions);
            }
            res.add(map);
        }
        return res;
    }